Lecture series on SES and capability-based security by Mark Miller

Allen Wirfs-Brock allen at wirfs-brock.com
Fri Nov 4 16:44:59 PDT 2011

On Nov 4, 2011, at 2:49 PM, Brendan Eich wrote:

> On Nov 4, 2011, at 2:40 PM, Allen Wirfs-Brock wrote:
>> On Nov 4, 2011, at 2:33 PM, Brendan Eich wrote:
>>> ...
>>> If you could redefine [] as an operator on all objects, perhaps that would help. Or hurt. Both, probably. That isn't what Allen proposes, though. It would have to be universal AFAICT. Thoughts?
>> Actually, that sounds pretty much what I proposed.  My proposal was that [ ] (actually RHS and LHS independently) would invoke a method using a well known property name if it was present on the object to the left of the [ ].  If the property was not present (own or inherited) then it would fall back to current behavior.
> So Object.prototype customization would cover all cases? Except Proxies, of course -- and host objects.

Yes, except that what you would expect to put into Object.prototype would actually (or also) be defined as default behavior in order to ensure that that Object.create(null) objects, etc continue to have ES1-5 behavior.  Because collection behavior is defined via  method invocation, proxies don't  need to do/have anything special (although a Proxy's [[Get]] handler) could look for accesses to the special [ ] behavior methods.  Same for host objects, except who knows what a host object really is...


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